cgroup: use kzalloc() instead of kmalloc()

There's no point in using kmalloc() instead of the clearing variant
for trivial stuff.  We can live dangerously elsewhere.  Use kzalloc()
instead and drop 0 inits.

While at it, do trivial code reorganization in cgroup_file_open().

This patch doesn't introduce any functional changes.

v2: I was caught in the very distant past where list_del() didn't
    poison and the initial version converted list_del()s to
    list_del_init()s too.  Li and Kent took me out of the stasis
    chamber.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ef97bd0cd5460e6970c3b5e6a84d228b2174a7cb..d86a8477d56a525383c761709b6cdf3205d88eca 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -597,7 +597,7 @@ static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
        INIT_LIST_HEAD(tmp_links);
 
        for (i = 0; i < count; i++) {
-               link = kmalloc(sizeof(*link), GFP_KERNEL);
+               link = kzalloc(sizeof(*link), GFP_KERNEL);
                if (!link) {
                        free_cgrp_cset_links(tmp_links);
                        return -ENOMEM;
@@ -658,7 +658,7 @@ static struct css_set *find_css_set(struct css_set *old_cset,
        if (cset)
                return cset;
 
-       cset = kmalloc(sizeof(*cset), GFP_KERNEL);
+       cset = kzalloc(sizeof(*cset), GFP_KERNEL);
        if (!cset)
                return NULL;
 
@@ -2475,10 +2475,12 @@ static int cgroup_file_open(struct inode *inode, struct file *file)
        cft = __d_cft(file->f_dentry);
 
        if (cft->read_map || cft->read_seq_string) {
-               struct cgroup_seqfile_state *state =
-                       kzalloc(sizeof(*state), GFP_USER);
+               struct cgroup_seqfile_state *state;
+
+               state = kzalloc(sizeof(*state), GFP_USER);
                if (!state)
                        return -ENOMEM;
+
                state->cft = cft;
                state->cgroup = __d_cgrp(file->f_dentry->d_parent);
                file->f_op = &cgroup_seqfile_operations;
@@ -3511,7 +3513,7 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
                }
        }
        /* entry not found; create a new one */
-       l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+       l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
        if (!l) {
                mutex_unlock(&cgrp->pidlist_mutex);
                return l;
@@ -3520,8 +3522,6 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
        down_write(&l->mutex);
        l->key.type = type;
        l->key.ns = get_pid_ns(ns);
-       l->use_count = 0; /* don't increment here */
-       l->list = NULL;
        l->owner = cgrp;
        list_add(&l->links, &cgrp->pidlists);
        mutex_unlock(&cgrp->pidlist_mutex);